The present invention relates to a method and a device for cushioned stoppage and accompanying of containers along a conveying line for containers. The method and the device are applied to containers or similar objects transported or conveyed to the feeding group of machine intended for processing thereof. When a row of bottles, or other types of fragile containers, transported on a conveying or feeding system of the known type stops, there is the risk that the said containers may be damaged owing to the effect of the sudden deceleration.
This is all the more true the greater the speed of the containers and the smaller the stoppage space.
Moreover, by intervening in some way from the outside in order to stop the line of containers, there is the risk that the remainder of the containers not stopped, i.e. those located between the intervention zone and the feeding zone of the machine situated downstream, will fall along the conveying line as a result of the sudden lack of pressure normally exerted by the row of containers situated behind.
The lack of a sufficient thrusting force or pressure may also prevent the entry of the containers into the feeding device of the machine situated downstream. The stopping devices of the known type are generally positioned slightly before the machine entry point and are activated in the case of sudden stoppages of said machine so as to prevent it from continuing to be fed with the containers.
The stopping devices thus allow stoppage of the machine or the entry conveyor to be avoided.
The stopping devices must allow gradual slowing down of the containers (so as to avoid breakage and damage) and must at the same time prevent some containers from going beyond the stopping device.
DE-A-3015203 discloses a stopping device which uses a rotating star wheel which always interferes with the containers and is mounted on a support which is able to translate parallel to the direction of conveying of the containers along a section limited by eyelets, being moved by the rod of a first pneumatic cylinder which acts as a cushioning member. The rod of a second pneumatic cylinder, mounted on the support, locks the rotation of the star wheel, which therefore acts a member for stopping the containers. After locking of the star wheel, the support is pushed by the pressure exerted by the row of containers which is kept in equilibrium by the cushioning member. A first drawback arises from the fact that when the shape or size of the containers changes, the star wheel must be changed.
Moreover the abovementioned device is unable to prevent falling of the last container which is not stopped and which continues towards the machine downstream without any support behind.
A further drawback consists in the high level of noise produced by the star wheel which always interferes with the containers and is made to rotate by the feeding movement of said containers.
DE 3622980 discloses a device similar to the preceding device in which the cushioning member moves a carriage which supports the stopping member. In this case the stopping member consists of a segment actuated by a lever mechanism moved by the rod of a pneumatic cylinder.
In this case the noise level is reduced and the stopping member probably does not have to be changed when there is a change in the shape or size of the containers, but in any case there still remains the problem of falling of the last container which is not stopped and moreover the mechanism described in the aforementioned document is somewhat complex.
Moreover, during activation of the se gent and its introduction into the path of the containers, it is possible that the containers may be compressed and damaged. Both the documents described above have the drawback that they require the use of two pneumatic cylinders one for cushioning and one for activation of the stop element. Moreover the cylinder situated on the carriage must be provided with flexible guides which may be easily damaged.
DE-A-3740014 discloses a stopping device which proposes eliminating some of the aforementioned drawbacks by means of use of a cushioning cylinder which moves an actuating element between an enabled upstream conveying position and blocked downstream conveying position.
The actuating element supports the stopping element and regulates the activation thereof by means of its movement between the two positions described above. In this case also, however, the last container of the containers which are not stopped tends to fall since it does not have any rear support.
GB 2090804 discloses a grouping apparatus for articles to be packaged, which uses fingers driven at different speeds to cause gaps between group of bottles on a conveyor belt. However the leverism which moves the fingers is rather complex and inadequate for conveyor belt travelling at high speeds.